January 17, 2002

Linux virtual machines aren't just for the big boys anymore

Author: JT Smith

- By Grant Gross -

If you watch any television, you've probably seen the commercial called "The Heist" this fall. A panicking manager type leads police detectives into what appears to be an empty server room. "It's the crime of the century!" the balding, middle-aged, middle manger exclaims over cheesy adventure-movie background music. "Everything's gone!"

"What was stolen?" asks one of the cops.

"Everything," the pointy-haired boss answers, "payroll, R&D, customer records ..."

Of course, our hero, a scruffy-looking geek boy, saves the day. He points to a mainframe in the back of the room, and says, "We moved everything onto that one. It's going to save us a bundle. I sent out an email ... "

The music swells, and the announcer says something about IBM servers running Linux saving you a bundle. What the commercial doesn't tell you is that the spendy IBM server in the commercial is running multiple copies of Linux at one time as virtual machines.

The concept of virtual machines -- sometimes called virtualization, virtual environments or virtual servers -- isn't particularly new, with IBM's VM operating system debuting 20-plus years ago. (The term "virtual machine" is also used to describe a VMware product that allows Linux and Windows to run side by side on a single machine.) But it's gaining popularity as companies seek to rein in hardware and management costs, and in some cases, reduce rent paid for the space to house huge server farms.

The IBM commercial doesn't say -- and why should it? -- that virtual machines can work well on low-cost servers and workstations, and at least a few companies -- including VMware, SWsoft and Ensim -- are pitching Linux VM-like technology for companies that can't afford a $1 million-plus IBM zSeries mainframe. There's even a Linux kernel-related project announced this fall that allows "virtual private servers" in Linux, and other Open Source projects. Other companies pitch technology such as virtual databases.

ConsultingTimes.com has an mpeg download of the Heist commercial, plus a recent cost comparison of IBM's setup vs. Microsoft Exchange. The article suggests the IBM solution may not be more cost-effective than Microsoft Exchange for server functions at companies with fewer than 5,000 users. However, when you're talking about a company with more than 25,000 users, the IBM mainframe's power quickly drives down the cost per seat to far below the Microsoft cost.

What's a virtual machine?

The virtual machine concept allows many copies of an operating system -- in this case Linux -- to run on one computer, but each acts independently. The companies pitching VM-like technology accomplish this in different ways, but generally, VMs can run stand-alone, or those operating systems can work together on the machine. The goal, says Susan DeKeukelaere, IBM's program director for zSeries marketing, is to maximize the processing power of your hardware.

"That VM operating system has evolved over time to be extremely powerful," DeKeukelaere says. "Today what we're finding is there are customers who have have large number of distributed servers running different tasks. Now, what they're finding is that the manageability of those gets to be very complicated as the number of those increases over time."

Consolidating those servers into a single "footprint" can save server management costs, she says. In some cases, companies running IBM zSeries with Linux virtual machines are running hundreds, and even thousands, of images of Linux on one box.

DeKeukelaere says power consumption costs can be reduced, and space can also be a "big, big factor" in cost savings, "especially on the West Coast, as real estate was getting very expensive. You've literally got rooms full of servers that can take up a lot of real estate."

John Krystynak, director of product marketing for VMWare, which is marketing virtualization on lower-cost Intel-based workstations and servers, says saving money on hardware is appealing, but more important, the VM technology allows customers to move functions between machines, in essence divorcing software and operating system decisions from hardware-buying decisions.

"What this virtual technology is doing is allowing people to say, 'I don't need to tie it together. I can do more than one thing on each machine safely, and I can move things around easily, so I don't have to be tied to that platform,'" he adds.

Reducing hardware management costs can also be a big selling point to VM technology, Krystynak adds. "Nowadays, the problem is you turn around and you suddenly have 40 servers in an organization with 800 people," he says. "Out of those 800 people, you have eight guys managing those servers. (IT directors) think, 'What would I rather have -- would I rather have 40 or 50 or 100 servers to manage or would rather have 10 more powerful, more controllable machines with more things running on them.'

"Yes, it does contribute to hardware cost savings, but in terms of overall cost -- if you look at Gartner or or Giga or Forester --hardware and software is only 15 percent of overall cost, so there has to be another reason to do it," he adds. "That other reason is people want to get their minds around this concept of much more manageable environments -- reducing the complexity, adding flexibility, and that's what this virtualization stuff does. It goes from, 'I can reduce my hardware cost by 10 percent,' to, 'If I can reduce the cost of labor of managing the machine, the cost of operations, the amount of space the machines take up, and make the buying of machines more uniform,' it can go from saving 10 or 15 percent of total cost to saving 40 percent of total cost."

The advantage of Linux

Linux has a couple of advantages in a VM setting, according to DeKeukelaere and Krystynak. Because of its relatively small size, you can pack lots of instances of Linux on one machine, says DeKeukelaere.

Krystynak, whose company markets VM technology that works both with Windows and Linux, points to Linux's cost as an advantage to those companies wanting to save money. He sees Linux VMs used most often for Web-serving or in scientific computing labs. "It's free is the biggest advantage," he says. "That means you can make as many virtual machines as you want without adding the new cost factor of adding another OS each time you make a virtual machine, where on the Windows side, you have to pay for licenses."

But Krystynak also says there are companies, especially Fortune 1000 companies in the United States, still nervous about making the switch to Linux. "The (license) cost factor isn't a platform-changing decision," he says. "It's just not big enough ... If companies are already considering Linux, they will be happy about it."

SWsoft aims at Web-hosting companies

For SWsoft, which focuses its Virtuozzo virtual Web-serving environment toward Web-hosting companies, Linux was the easy choice, says Craig Oda, v.p. of business development, because Linux is a much-used Web-hosting OS.

SWsoft, which announced the 2.0 version of Virtuozzo last week, is selling its virtual environment to Web-hosting companies as a way to pack more customers on each server. The company pitches Virtuozzo as "mainframe-like partitioning and manageability on the commodity hardware and operating systems," and with large Web-hosting companies like Exodus struggling to make money, the industry needs a low-cost way to bring small- and medium-sized businesses to their customer base, Oda says.

SWsoft's technology allows up to 800 copies of Web-hosting Linux on a single, Intel-based server, Oda says, each with its own root access, although it'd take a pretty powerful box for you to do that. "It's like a mainframe on an x86 box," he says. "What we're doing on x86 is what IBM is doing on mainframes. The customer is paying through the nose for (IBM). Our solution is a quantum leap in cost savings for them."

The company's virtual environment, which Oda says has 11 patents pending, now runs only on Linux, but there's a port to Solaris in progress, and the company eventually plans to offer it for Windows, too. SWsoft's presentation on virtual environments already comes on Power Point.

Virtuozzo, along with the company's HSPcomplete hosting automation package, allows automated HSP operations now very manual: management of hardware, updating and upgrading, Oda says. Customers can be moved from box to box, allowing a more efficient use of hardware, he adds.


Like SWsoft, Ensim's Private Server technology is aimed at Web-hosting companies and Internet service providers. The company's product can "fractionalize" physical servers into as many as about 100 virtual Web servers, says Andy Kim, Ensim's v.p. of marketing.

"As a service provider, I can take a box and split it up into four virtual servers and guarantee that each of the customers of the partitions have access to, at the minimum, one quarter of the computing resources," Kim says. "But if the others are idle, they can use more than a quarter of their resources."

Again, this allows more efficient use of hardware resources, Kim says. As many as 100 partitions can be useful for copying a relatively low-powered application, like a firewall, and running them all on one box.

Kim claims Ensim's way of doing a virtual environment, by creating logical dedicated servers, sucks up fewer computing resources. The Private Server technology works on any Linux-based box, not just Intel-based, he says.

"The virtualization layer is optimized for performance, so it only imposes a very minimal overhead," Kim says. "It gives the service provider the flexibility to take any Linux box and split it up. It can be a single CPU box, and they can split that up and offer different services on it."

The patent-pending technology, he says, offers several "dimensions of isolation," as he calls it. The virtual servers include performance and fault isolation, meaning that if there's an OS-level fault on partition, the other virtual servers on the box would continue running. "I would be surprised to find others that guarantee 100% fault isolation, that's the hardest thing to do, and at the same time, keep the performance overhead down below 5%."

Ensim's technology allows easy migration between boxes, and has other management features, he says. "Our partitions are intelligent partitions, in that they're containers that only only regulate the resources that partition is using, but they monitor the health of the applications, and they allow us to migrate applications from one partition to another."

Ensim's virtualization technology is available for Linux and Solaris, and the company's 3-year-old Private Server technology has lead to partnerships with IBM, Sun and Compaq.


VMware is well-known in the Linux community for its VMware Workstation product that allows Linux and Windows to run at the same time on a box, largely for developers who are testing more than one OS environment. However, VMware also offers its GSX Server, which partitions servers to several virtual machines running Linux or Windows.

"We're virtualizing the Intel architecture," says Krystynak, director of product marketing. "We're bring that (IBM zSeries) concept down to the Intel side."

Krystynak says VMware tells customers they can put four to 20 virtual machines onto one box, but he stresses that these are complete operating systems, not just Web servers. Like competing products, these virtual machines are isolated from each other, so if one crashes, the others don't.

Krystynak says the virtualization concept is starting to become popular across the range of platforms. "The thing that's new, if you look at the high end with the mainframes and you look at the mid end with a departmental enterprise server, you've had techniques to do be able this all along because people make a big hardware investment and they want to be able to use it in more than one way," he says. "Now, the reason it's starting to gain popularity in a broader way is you actually can do it from a desktop all the way up to a data center. Frankly, the same thing that's happened on mainframes where the hardware is clearly overpowering for two users, nowadays you can buy an Intel server and think the same way: 'Man, the hardware really can do a lot more than just dedicating one app on it.' So why not take advantage of that?"

Krystynak says the cost savings that virtual servers can bring is an appealing message, especially right now. "Companies are like, 'If you don't spend this money the next three months, you might have the privilege of working here six months from now.' "

While VMware sells more Windows software, the company has several customers using GSX with Linux, Krystynak says. One example is Global Continuity, a disaster recovery service company. Global Continuity insures other company's machines and provides immediate recovery or replacement of critical machines.

"It's expensive do to this," he says. "It's kind of an insurance business, where basically you're saying, 'We know how often people fail, we know what the rate of failures is, and we know how many machines we need to cover.' "

With GSX Server, Global Continuity can pack five or six customers on a single box, Krystynak says. When a customer's system fails, Global Continuity copies the customer's information onto one box and sends it out. "By eliminating the need to do one-to-one mirroring, they're seriously reducing their hardware and maintenance costs."

Virtual servers for the Linux kernel

In October, Linux developer Jacques Gelinas sent out an announcement about his vserver project, which he says allows users to "run general purpose virtual servers on one box, full speed!"

Gelinas wasn't available for an interview, but his vserver project is explained at http://www.solucorp.qc.ca/miscprj/s_context.hc. There, Gelinas suggests that virtual servers can be used by anyone managing a server. He suggests another advantage in addition to cost savings: Easier security management of multiple servers.

"Linux computers are getting faster every day," he writes. "So we should probably end up with less, more powerful servers. Instead we are seeing more and more servers. While there are many reasons for this trend (more services offered), the major issue is more related to security and administrative concerns. Is it possible to split a Linux server into virtual ones with as much isolation as possible between each one, looking like real servers, yet sharing some common tasks (monitoring, backup, ups, hardware configuration, ...)? We think so."

The current version of vserver is 0.9. It's available for download and released under the GNU GPL.


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